I. Field of the Invention
The present invention relates to conveyor systems including a support providing a path along which trays are movable in a forwarding direction and, in particular, the present invention relates to pusher members for drivingly engaging such trays and moving the same.
II. Description of the Prior Art
The prior art contains numerous examples of accumulating conveyor systems, and examples of such systems are disclosed in U.S. Pat. Nos. 1,742,789; 2,635,555; 2,645,186; 2,741,190; 2,961,973; 3,099,228; 3,434,431; 3,437,054; 3,559,586; 3,623,538; 3,661,094; 3,799,327; 3,837,289; USSR Pat. No. 250,031; and German Pat. No. 1,194,325. Two of the aforementioned patents, namely, United States Letters Patent Nos. 3,799,327 and 3,837,289, disclose conveyor systems and pusher mechanisms which, in the opinion of the inventor, represent the closest prior art known to the inventor. These patents disclose conveyor systems that have plural endless and independently powered conveyor chains, which travel on individual guide tracks traversing the entire length of the system, and one or more further and similar chain and track-type branch lines which, at spaced zones there along, converge and diverge in relationship to the main line. Trays are moved along the tracks by means of pusher members or dogs attached to the endless driven chain. In certain of the aforementioned patents the pusher member is pivotally mounted and associated with a pivoted control member located forwardly of the pusher member and connected thereto by a link, the two members being normally urged to positions in which the pusher member is drivingly engageable with the tray and the control member is engageable with an object such as the preceding tray overtaken by the control member. Such engagement results in movement of the pusher member to a non-driving position and enables trays to be stopped and accumulated. In both of the last two aforementioned patents the connection between the control member and the pusher member is accomplished by means of a toggle arrangement that generally comprises a link having at least one end pivotally connected to a body of the pusher mechanism and its other end having a connection with the pusher member, whereby the pusher member can be releasably locked in an operative position and moved therefrom in conjunction with the swinging motion of the link, while suitable means are provided for connecting the link with the control member, whereby movement of the control member out of its raised position imparts a swinging motion to the link and, thus, brings the pusher member to an inoperative position. In both of the aforementioned patents a cam follower is secured to the control member and is selectively engageable with movable cam tracks. One type of cam track so disclosed produces movement of the pusher member to a non-driving position, when engaged by the cam follower, and is combined with an abutment for stopping the tray being driven by the pusher member.
While each of the aforementioned United States patents disclose conveyor and pusher mechanisms which have performed in a generally satisfactory manner, the use of the toggle-type linkages presents problems in its practical applications; and, as such, it would be desirable to provide a pusher mechanism which requires neither the toggle-type linkage or the cam followers as a means for selectively moving the pusher mechanism between an operative and an inoperative position.